Buckthorn was a rabbit who came to the Watership Down Warren from the Sandleford Warren. He was a strong rabbit who was going to join the Sandleford Owsla, when he reached full weight. He was described as a tough, sturdy rabbit with a quiet and easygoing nature. Like Silver, he is steadfast and dependable in a crisis.
He was injured by a rat while the group was resting in a barn following the ordeal in the Warren of Snares. Buckthorn, along with Holly, Strawberry, and Silver, went to Efrafa to ask if they could have a few does join their warren; he came back injured from a blow across the face. Following the Battle of Watership Down, he later joined the Watership Down Owsla.